Sahih al-Bukhari 6738
Sahih al-Bukhari · Book 85: Laws of Inheritance (Al-Faraa'id) · The shares of inheritance for the paternal grandfather, the father and brothers
Narrated Ibn `Abbas:
حَدَّثَنَا أَبُو مَعْمَرٍ ، حَدَّثَنَا عَبْدُ الْوَارِثِ ، حَدَّثَنَا أَيُّوبُ ، عَنْ عِكْرِمَةَ ، عَنِ ابْنِ عَبَّاسٍ ، قَالَ أَمَّا الَّذِي قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " لَوْ كُنْتُ مُتَّخِذًا مِنْ هَذِهِ الأُمَّةِ خَلِيلاً لاَتَّخَذْتُهُ، وَلَكِنْ خُلَّةُ الإِسْلاَمِ أَفْضَلُ " . أَوْ قَالَ " خَيْرٌ ". فَإِنَّهُ أَنْزَلَهُ أَبًا. أَوْ قَالَ قَضَاهُ أَبًا .
The person about whom Allah's Messenger (ﷺ) said, "If I were to take a Khalil from this nation (my followers), then I would have taken him (i.e., Abu Bakr), but the Islamic Brotherhood is better (or said: good)," regarded a grandfather as the father himself (in inheritance).